THE UNIVERSE AS A HOLOGRAM

Prof Stephen Hawking's closest collaborator explains emerging evidence indicating the cosmologist's final thoughts on time were correct and why this suggests the Universe might be a giant hologram

- by PROF THOMAS HERTOG

A centrepiece of Prof Stephen Hawking's theory of black holes states that black holes can only grow.

Thanks to precision observations made with the Laser Interferometer Gravitational-Wave Observatory (LIGO), this theory has now been verified for the first time. This marks a new milestone exactly 10 years after LIGO's first detection of gravitational waves.

Above all, it demonstrates that advanced observations of gravitational ripples can reach into the deepest roots of physics. In the future, they may even reveal that the Universe is a hologram.

TIME WITHOUT TIME

The theoretical discovery that there might be a hologram hiding underneath our familiar reality of space and time ranks among the most important, baffling and far-reaching physics discoveries of the late-20th century. Physicists still don't agree on what form this hologram might take, but just the mere idea of a hologram has opened up implications that have already changed theoretical physics beyond recognition.

For decades, physicists had struggled to seal the marriage of General Relativity and quantum theory. The discovery of holography did exactly that. It showed that gravity and quantum theory need not be water and fire, but can be like yin and yang: two very different yet complementary descriptions of the same physical reality. Physical systems can be gravitational and quantum at the same time, holography says, albeit in different dimensions. This is the shift in perspective brought about by holography.

Perhaps our entire expanding Universe might be a hologram – this is Hawking's final theory of the Universe. In the holograms we're familiar with, a third dimension of space emerges from the light projected on a surface. In the cosmos-as-a-hologram idea, however, it would be the dimension of time that can be holographically encoded. That is, the evolution of the Universe might be a holographic projection.